Ultrasonic cleaning apparatus for preparing articles for coating



United States Patent [72] Inventor Wayne D. Patterson Nashua, Iowa [21] Appl. No, 700,170 [22] Filed Jan. 24, 1968 [54] ULTRASONIC CLEANING APPARATUS FOR PREPARING ARTICLES FOR COATING 10 Claims, 10 Drawing Figs.

[52] US. Cl 118/73, 134/1, 134/66, 134/80, 134/83, 134/163 [51] Int. Cl B08b 3/10, B05c 11/16 [50] Field ofSearch 134/1, 83, 133,147,157,161,163,165,184, 66, 80-82; 118/72, 73

[56] References Cited UNITED STATES PATENTS 1,201,475 10/1916 Lank 134/66 1,877,817 9/1932 Cook..... 134/83UX 2,702,260 2/1955 Massa 134/157X 2,784,119 3/1957 McCown et al.. 134/184X 2,950,725 8/1960 .Iacke et a1 134/184 2,985,003 5/1961 Gelfand et a1. 134/184X 3,026,885 3/1962 Eytinge 134/184X ,z M I02 [a7 Primary Examiner-Robert L. Bleutge Attorney-Burd, Braddock & Bartz ABSTRACT: An apparatusand method for cleaning concrete from a pallet or tongue former used in the production of concrete pipe. The apparatus has a conveyor which sequentially moves pallets to a soaking position to a scrubbing position and to a coating position. In the soaking position the pallet is immersed in a liquid solvent chemically operable to weaken the structure of the concrete on the pallet. From the soaking position the pallet is moved to the scrubbing position onto a rotatable turntable located in the liquid solvent. Ultrasonic energy units are positioned in the liquid in close proximity to the pallet on the turntable. The ultrasonic energy units subject the concrete on the pallet to cavitation action which removes the concrete from the pallet. The cleaned pallet is raised from the liquid and discharged onto a rotatable floor which directs the pallets through a coating chamber. In the coating chamber the cleaned pallets are covered with a coating material to protect the pallets for temporary storage, neutralizes the cleaning chemical residue and provides a release surface for the concrete in further use of the pallet.

Patented Nov. 10, 1970.

Sheet All /YE .D. P19775250 I Ban Mac ac/mn, fiaad'dbc,

Patented Nov. 10, 1970 Sheet 3 of 4 I N VE N TOR.

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ULTRASONIC CLEANING APPARATUS FOR PREPARING ARTICLES FOR COATING BACKGROUND OF INVENTION It is common practice to clean precision concrete pallets and tongue formers with steel brushes, grinders, steel wool, chisels hammers and other like implements. This is a costly and time-consuming process and many times is detrimental to the pallets. Ultrasonic cleaning is a widely used industrial tool for cleaning electronic parts, optical elements, filters and complete electromechanical assemblies as well as for the degreasing of manufactured parts. Other production techniques as ultrasonic quenching, chemical milling and chemical processing utilize the use of cavitational energy in a liquid medium. These systems employ a transducer fitted tank that develops ultrasonic cleaning power in a cleaning media in the tank. Examples of this type of ultrasonic cleaning systems are described in US. Pat. Nos. 2,947,889 and 2,956,538.

SUMMARY OF INVENTION The invention relates to an ultrasonic cleaning apparatus for removing foreign material from an article. The apparatus has a tank for storing a cleaning liquid. Located within the tank is a support means for holding at least one article in the liquid. The support means is driven so that the article can be moved in the liquid. An ultrasonic energy system including a vibrator means positioned in the liquid subjects a limited area of the liquid to vibrational energy which produces localized gas pressure and cavitational action on the foreign material attached to the article. This cleaning action together with the moving liquid effectively removes all of the foreign material from the article with a minimum of time and effort. By using a plurality of vibrator means, selected areas of the article can be subjected to the ultrasonic cleaning process. After the cleaning operation has been completed, the article is transported to a coating means operable to apply a protective coating to the outer surface of the cleaned article.

The invention also contemplates a method of cleaning an article by moving the article into a soaking position and then soaking the article in a liquid solvent to weaken the structure of the foreign material on the article. After the article has been soaked in the liquid solvent for a period of time the article is transported to a scrubbing position. In the scrubbing position the article is moved relative to a plurality of spaced ultrasonic vibrator means operable to subject selected areas of the liquid adjacent the moving article to a cavitational action, moving liquid and pressure which removes the foreign material from the article. After the article has been cleaned it is removed from the liquid solvent and covered with coating material.

IN THE DRAWINGS FIG. 1 is a plan view of the cleaning apparatus of the invention;

FIG. 2 is a side view of the cleaning apparatus shown in FIG. 1;

FIG. 3 is an enlarged sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a view similar to FIG. 3 showing the pallet in the soaking position and the cleaning position;

FIG. 5 is an enlarged sectional view taken along the line 5-5 of FIG. 2;

FIG. 6 is an enlarged side view of a pallet transfer finger;

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 6;

FIG. 8 is an enlarged sectional view taken along the line 8-8 of FIG. 5;

FIG. 9 is an enlarged sectional view of a portion of a pallet showing the chemical weakening action on the pallet; and

FIG. 10 is a view similar to FIG. 9 showing ultrasonic scrubbing action on the pallet.

Referring to the drawings there is shown in FIGS. 1 and 2 the cleaning apparatus of this invention indicated generally at 15. The apparatus is a highly efficient and reliable ultrasonic cleaning system operable to sequentially clean articles of various sizes by the use of the effects of vibrational energy in a liquid medium. The apparatus comprises a receiver 16 for" operable to sequentially move the articles 19, 19A, 19B and 19C in the direction of the arrow 22 through the apparatus.

The article is shown as an annular ring pallet 19 used in making cement pipes. Pallet 19 is used by way of example in describing the apparatus. Other types, sizes and shapes of articles can be cleaned with the apparatus. The foreign material on the article varies from cement to oil and may include any material.

The receiver 16 is in the form of a generally horizontal table having side frames 23 carrying a plurality of transverse rollers 24 used to support the article 19. Receiver 16 is joined to the forward end of the cleaner 17 thereby enabling the conveyor 21 to move the article 19 from the receiver to the soaking position in the cleaner 17.

Cleaner 17 comprises a tank 26 having an open top supported on a frame 27. A liquid cleaning solvent 28 is located in the tank. The liquid is selected from a number of known chemical cleaning solutions to react with the foreign particles on the article to produce a chemical cleaning action. An example of the chemical used to remove cement from an annular pallet ring is a solution of muriatic acid and a rust inhibiter sold as Oakite 32. The temperature of the cleaning solvent 28 is regulated by an external source of heat supplied to a steam line 29 controlled with a valve 31. In some cleaning operations the temperature of the liquid solvent is maintained in a range of between and F.

As shown in FIG. 5, a carriage indicated generally at 32 located within tank 26 is moved in a vertical direction into and out of the tank by a pair of hydraulic cylinders 33 and 34. The carriage 32 has a horizontal base 36 carrying upright legs 37 and 38. Secured to the upper end of legs 37 and 38 are outwardly directed brackets 39 and 41 which extend around upright guide rails 43 and 44 respectively. Pairs of upper and lower cooperating rollers 46, 47 and 48, 49, shown in FIG. 8", rotatably mounted on the bracket 39 engage opposite sides of the rail 43 to movably mount the carriage on the rail. Bracket 41 has similar rollers which movably mount the leg 38 on the rail 44.

The base ends of the cylinders 33 and 34 are secured to outwardly directed horizontal supports 51 and 52 attached to opposite sides of the frame 27. The upper ends of the piston rods extended from cylinders 33 and 34 have crevices 53 and 54 pivotally mounted to the brackets 39 and 41. On extension of the piston rods 33 and 34, the carriage 32 is raised as shown in broken lines in FIG. 5 moving the base from the cleaning solvent 28.

As shown in FIG. 3, the base 36 of the carriage separates the tank into two working stations. The first station has a moving platform comprising a plurality of spaced longitudinal bars 56 carried on crossbars 57. A beam 58 connects the crossbars with the base so that the platform moves up and down with the carriage. Located on the opposite side of the platform is an arm 59 carrying a movable support or rotatable turntable 61.

The upper face of turntable 61 has a plurality of radial ribs 62 used to support the work article 19C on the turntable. On rotation of the turntable the ribs function as vanes or blades causing the liquid solvent to circulate in the tank aboutthe article.

Returning to FIG. 5, projected downwardly from the midportion of the base of the turntable 61 is an upright shaft63 rotatably mounted in a bearing 64. The bearing 64 is secured to an outer portion of arm 59. Located between the turntable and the arm 59 is a sprocket 66 mounted on the shaft 63. A chain 67 is trained about the sprocket 66 and a sprocket 68 carried on an upright shaft 69. The upper end of the shaft 69 is connected to a motor 71. The motor 71 located above the level of the liquid solvent 28 is carried on a bracket 72 secured to the upper part of the leg 37. A coupling 73 attaches the motor to the shaft 69. The lower end of shaft 69 is carried in an upright sleeve bearing 74 mounted in the base 36. The speed of the motor 71 is regulated by a control 75 mounted on the side of tank 26. This control allows the operator to change the speed of movement of the article in the cleaning position.

As seen in FIGS. 1 and 5, a semicircular shelf 76 secured to the inside of tank 26 extends toward the turntable 61. Shelf 76 has a substantially flat upper surface generally aligned with the top surface of the turntable when the turntable is in its lowered position.

The chemical weakening action of the liquid on the structure of the concrete is combined with ultrasonic vibrations established by an ultrasonic system indicated generally at 77. The ultrasonic system 77 comprises an ultrasonic generator 78 mounted on the frame structure adjacent the tank 26. Movably positioned on the shelf 76 are a plurality of vibrators or transducers 79, 31 and 82, 83. Cables 84 connect the transducers to the generator 73. As shown in FIG. 3, the transducer 82 has a bottom area enclosing a weight 86 used to hold the transducer in a selected location on the shelf 76. Each transducer has a similar weight so that they can be moved on the shelf relative to each other and relative to the article on the turntable.

The ultrasonic generator 78 may vary in size and number used according to the size and requirements of the cleaning operation. Generators rated at 150, 250, 500 and 1,000 watts average deliverable output power operating at a frequency of 22 kilocycles can be used to provide the required intensity of cleaning power. An example of a suitable transducer is a transducer having a lead zirconium titanate element sandwiched in compression between metal blocks. These transducers are provided with weighted bottom portions to hold the transducers on the shelf 76.

The coater 18 located adjacent the rear end of the tank is operable to receive the clean article and cover or coat the article with a liquid material which protects the articles in storage and neutralizes the cleaning chemical residue which still may be on the article. The coating material can also be a release coat for further use of the article. The coater 18 has a pair of rearwardly and downwardly extended side members 88 and 39 carrying a plurality of spaced transverse rollers 91 forming a movable floor for supporting the clean article 19C. The roller floor is inclined in a downwardly direction so that the article 19C moves to the outer end of the coater through a housing 92 forming a spray chamber. Located within housing 92 are a plurality of transverse nozzles 93 connected by a pipe 94 to a pump 96. A motor 97 drives the pump 96 to withdraw the coating liquid from a tank 98. Excess liquid is collected at the bottom of housing 92 and returned to the tank through a return line 99.

Returning to FIGS. 1 and 2, conveyor 21 is positioned above and extended longitudinally over the receiver 16, cleaner 17 and the forward portion of the coater 18. In use, the conveyor 21 operates to sequentially move the pallet 19 to the soaking station, the cleaning station and the coating station in a manner so that separate pallets are in each stage of the cleaning operation. The conveyor 21 comprises a longitudinal rail 101 in the shape of an I-beam extended longitudinally along the center line of the apparatus. A pair of crossbeams 102 and 103 carried on the tops of pairs of upright side posts 10 1 and 106 support the ruil 101. The posts 104 and 106 are part of the frame 27 oithe apparatus. Positioned about the lower flange of the rail 101 are a pair of U-shaped members 107 carrying pairs of rollers 108 and 109 to rotatably support the members. An elongated channel 111 attached at its opposite ends to the U-shaped members 107 carries three downwardly projected transfer fingers 1 12.

As shown in FIGS. 6 and 7, the channel 111 has an opening 113 allowing the finger 112 to project downwardly toward the tank. Transverse pin 114 rotatably mounts the finger on the flanges of the channel. Positioned rearwardly of the finger and opening 113 is a downwardly projected stop 116 used to hold the finger in an upright position by limiting the pivotal movement of the finger to a forward'and upward direction as indicated by arrow 117. Each finger 112 on the channel 111 is mounted in a similar manner.

The channel 111 is reciprocated along the rail 101 by a cylinder 118 secured to the forward end of rail 101. Projected forwardly from the cylinder 118 is a piston rod 119 connected to the forward end of the channel 111.

In use, the articles or pallets are initially placed on the rollers 24 of the receiver 16 in alignment with the conveyor 21. As shown in FIG. 3, on extension of the piston rod 119, the first finger 112 moves the pallet 19A onto the elongated bars 56 of the soaking platform. The carriage 32 is in a raised position aligning bars 56 with the ends of the receiver. This is accomplished by extending the cylinders 32 and 33 as shown in dotted lines in FIG. 5. Each pallet is sequentially moved through the cleaning apparatus in a three step operation. On extension of piston rod 119 the middle finger moves the pallet 193 from the soaking platform onto the top of the turntable 61. The forward finger 112 moves the pallet located on the turntable off onto the rollers 91 which lead through the coater 18.

On movement of the piston rod 119 into the cylinder 118 the channel 111 and the fingers 112 move back to their initial positions in alignment with the next series of pallets. The fingers are free to pivot forwardly over the pallets. The cylinder 1 18 is operated in a timed relation with the position of the carriage 32 so that the pallets are moved by the conveyor only when the carriage is raised.

To commence the cleaning operation the carriage 32 is lowered to submerge the articles in the cleaning solvent 28 as shown in FIG. 4. The pallet 19A is soaking in the solvent 28. The pallet 19B is in the cleaning position located on turntable 61 rotated on operation of the motor 71. As the turntable 61 rotates the peripheral portion of the pallet moves toward and away from the plurality of transducers 79, 81 and 82, 84 resting on the shelf 76. In addition, the upright radial ribs 62 on the turntable mixes the solvent in the tank and provides a washing action of the solvent against the foreign and dirt particles on the pallet. The movement of the solution agitates and mixes the solution to continuously maintain a substantially uniform concentration of the chemical in the solvent. In addition, the movement of the liquid solvent keeps the sand particles in suspension where they have an abrasive effect on the pallet moving with the turntable.

The ultrasonic system 77 produces high frequency energy which is transferred through and reacts with the liquid in the tank to provide a quick and reliable cleaning of the foreign material from the pallet. The ultrasonic generator 78 creates the high frequency energy and transmits it to the plurality of vibration devices or transducers 79, 81 and 82, 84 positioned on the shelf 76. The bottom of each transducer is weighted so that the transducer can be moved toward and away from the pallet as required to produce an effective cleaning operation.

As shown in FIG. 9, foreign material 122, as particles of cement and sand, are held on the pallet 19A by a cryptocrystalline matrix or protective coating 123 covering the machined surface of the pallet. In the soaking position the liquid cleaning solvent 28 chemically weakens the matrix 123 to an undetermined depth.

FIG. 10 shows the combined progressive and cyclic action of chemically weakening the matrix and the cavitational removal of the foreign material and weakened matrix when the pallet is in the scrubbing position. The removal of the matrix exposes the remaining matrix to further chemical weakening.

The ultrasonic vibrations created by the transducers irradiate the liquid cleaning solvent to cause liquid cavitation known as cold boiling. This action is produced by alternating periods of rarefaction and condensation which characterize intense sound waves 121 introduced into liquids. The alternating pressure of the sound waves 121 causes tiny bubbles of vapor to form in the liquid. The compression of the vapor causes the bubbles to implode in the area of the foreign material 122. The result is a continuing formation and subsequent collapse of an extremely large number of small trapped vapor bubbles creating an instantaneous localized high pressure. This high pressure moves the liquid at high velocities against every surface of the parts to be cleaned. This operation is a cavitation process and is repeated at approximately 22,00 times a second with the result that there is effi cient and safe removal of all of the foreign materials from the external surfaces of the pallet. This cavitation process coupled with the chemical reaction of the cleaning solution on the foreign material and the abrasive action of the moving particles in the liquid solvent provides efficient and quick cleaning of the pallets.

The coating 123 may be the temporary protective coating applied in the previous cleaning operation by the coater 18. In some pallets the coating is in the form of oil, varnishes and similar chemicals to protect the pallets from rust as well as to provide a release agent on the pallet for the cement pipes. lt is advantageous to remove the old coating and apply a smooth coating to the pallets before they are reused. The ultrasonic energy waves 121 in conjunction with the movement of the cleaning liquid provides cavitation, abrasion and pressures which clean the foreign material 122 from the surface of the pallet 19B as well as erode away the protective coating 123.

In terms of a method of cleaning foreign material from an article as concrete from a pipe forming pallet, the pallet is initially moved by the conveyor 21 to a soaking position on the longitudinal bars 56 of the carriage 32. The carriage is then lowered to locate the pallet in a heated liquid solvent operable to weaken the structure of the concrete and other foreign material on the pallet. During the soaking of the pallet the liquid solvent is moved around the pallet to wash away any concrete which may dissolve or fall away from the pallet as well as maintain substantially uniform concentration of the liquid solvent.

After the article has been soaked for a predetermined period of time it is transported from the soaking position to a cleaning position by the conveyor 21. At the same time a second or subsequent article is moved into the soaking position by the conveyor. In the cleaning position the article rests on the top of the turntable 61 which on operation of motor 71 rotates to move the article in the liquid solvent. The movement of the article has a washing effect on the foreign material as well as maintains the substantial uniformity in the concentration and temperature of the solvent. Simultaneously with the movement of the article a plurality of selected areas of the liquid solvent is subjected to ultrasonic vibration energy in areas adjacent the peripheral portion of the moving article. The ultrasonic vibration energy creates large localized pressures and establishes a cavitational process which effectively removes the foreign material from the pallets.

By subjecting the article to be cleaned with repetitive and localized ultrasonic vibration energy relatively large ratios of power to gallons of liquid solvent can be effectively used. For example, if full power were distributed throughout the tank an ultrasonic generator of approximately 100 watts per gallon of liquid would be needed to produce an effective cleaning of the pallet. In the present invention 150 gallons of cleaning solvent is effective with a 1000 watt generator operating at 22 kilocycles.

After the article has been cleaned it is elevated and moved from the movable turntable onto a floor which directs the cleaned pallet to the coating chamber. As the cleaned article moves through the chamber it is coated with a protective external layer or skin.

While there have been shown and described a preferred embodiment of the present invention it is to be understood that various changes and substitutions of material and parts may be made without departing from the spirit of the invention. For

example, it is contemplated that the rotatin turntable could atrve to transdube a reciprocating member which moves re cers located in the cleaning solvent. The invention is limited only by the terms of the following claims.

I claim:

1. A cleaning apparatus comprising a tank for storing a cleaning liquid, support means located in said tank for holding at least one article in said liquid, said support means including platform means for supporting an article, a carriage selectively movable into and out of the tank and a turntable rotatably mounted on said carriage for supporting a second article in the liquid, ultrasonic vibrator means positioned in the liquid in the tank adjacent the article. held by the support means, and means for moving the support means whereby the article moves relative to the vibrator means.

2. The apparatus of claim 1 wherein said turntable has rib means for moving the liquid on rotation of the turntable.

3. The apparatus of claim 1 wherein said tank has an inwardly directed shelf located adjacent the support means, said ultrasonic vibrator means being positioned on said shelf.

4. The apparatus of claim 3 wherein the ultrasonic vibrator means includes a weight for holding the vibrator means on the shelf.

5. The apparatus of claim 3 wherein a plurality of ultrasonic vibrator means are positioned on said shelf.

6. The apparatus of claim 1 wherein a plurality of ultrasonic vibrator means are positioned in said liquid.

7. The apparatus of claim 1 wherein the platform means is selectively movable into and out of the tank.

8. The apparatus of claim 1 including: conveyor means operable to move a first article onto the platform means and a second article from the platform means to the turntable.

9. A cleaning apparatus comprising a receiver for holding articles, a tank for storing a cleaning liquid, a platform in the tank for holding at least one article in said liquid in a first position, a rotatably turntable in the tank for holding at least one article in said liquid in a second position, carriage means for raising and lowering the platform and turntable relative to the tank whereby the articles on the platform and turntable are moved into and out of the liquid, a conveyor operable to sequentially move articles from the receiver to the first position, from the first position to the second. position and from the second position to a discharge location, and ultrasonic vibrator means positioned in the liquid in the tank adjacent the article held by the turntable.

10. The cleaning apparatus of claim 9 including a coating unit located adjacent said tank operable to receive articles from the second position and apply coating material to the external surfaces of the articles. 1 

